KR20170041707A - Stabilized Rhenium-based heterogeneous catalyst and use thereof - Google Patents

Abstract

The present invention relates to a stabilized rhenium-based heterogeneous catalyst obtainable by a process comprising contacting a rhenium-based heterogeneous catalyst with a stabilizer comprising an aliphatic hydrocarbon compound at a temperature ranging from 0 to 100 ° C, Lt; / RTI >

Description

Stabilized rhenium-based heterogeneous catalysts and uses thereof < RTI ID = 0.0 >

The present invention relates to a stabilized rhenium-based heterogeneous catalyst and a method for producing olefin compounds using the catalyst.

The metathesis reaction is used to convert olefins. In the metathesis reaction, the same or different kinds of olefins react with each other to produce olefins having different structures (for example, ethylene and butene are metathesis to produce propylene and butene is metathesis to produce pentene and propylene).

Various catalysts for olefin metathesis have been developed. Of these, catalysts with oxides of molybdenum, tungsten and rhenium supported on large surface area carriers are of the highest industrial interest.

Molybdenum- and tungsten-based catalysts are more widely used in industrial metathesis processes because of their high resistance to catalyst poisons and low cost. However, they are known to have low activity compared to rhenium, and therefore, in order to achieve the desired activity, a high temperature of generally above 100 ° C, preferably above 200 ° C is required. Conveniently, using higher temperatures reduces selectivity because side reactions such as olefin isomerization and oligomerization occur.

Rhenium has very high activity on olefin metathesis. Rhenium can be operated in a fairly low temperature range. However, rapid deactivation of rhenium is a major disadvantage.

European patent application EP 0273817 A1 discloses an olefin metathesis process which is carried out in the presence of a rhenium catalyst in a moving bed reaction zone, which is then reoxidized in a connected regeneration zone. This allows the process to operate continuously despite the high deactivation rate of the rhenium catalyst. However, moving bed processes are much more complex and energy consuming and are therefore generally less desirable in industrial applications, particularly in comparison to fixed bed systems.

U. S. Patent No. 6,277, 781 B1 discloses a method for reducing the rate of deactivation of a rhenium-based metathesis catalyst which is carried out in a hydrocarbon-containing stream (e. G., A methane stream) Treating the catalyst, and activating the catalyst in a non-reducing atmosphere at a temperature in the range of 400 to 1,000 DEG C before performing the metathesis reaction, wherein the catalyst preferably contains a certain amount of cesium.

It is therefore an object of the present invention to overcome the disadvantages of the prior art and to provide a stabilized rhenium heterogeneous catalyst which exhibits, in particular, improved reaction stability and resistance to toxic substances.

It is a further object of the present invention to provide a stabilized rhenium-based heterogeneous catalyst which enables the use of a catalyst in a fixed bed reactor.

It is a further object of the present invention to provide an improved process for preparing olefin compounds with increased operating cycle time.

This object is achieved by a stabilized rhenium-based heterogeneous catalyst and a process for the production thereof, wherein the process comprises contacting the rhenium-based heterogeneous catalyst with the stabilizer at a low temperature.

More particularly, the object is achieved by a stabilized rhenium-like heterogeneous catalyst obtainable by a process comprising contacting a rhenium-like heterogeneous catalyst with a stabilizer at a temperature in the range of from 0 to 100 < 0 > C, The stabilizer may include an aliphatic hydrocarbon compound.

Figure 1 shows the effect of the stabilizer on the conversion of 2-butene.
Figure 2 shows the effect of the stabilizer on propylene selectivity.
Figure 3 shows the effect of stabilization temperature on the conversion of 2-butene.
Figure 4 shows the effect of stabilization temperature on propylene selectivity.

The rhenium-based heterogeneous catalyst according to the present invention may comprise at least one compound selected from the group consisting of rhenium in the form of elemental metal and / or at least one rhenium compound (for example, rhenium oxide, rhenium hydride, rhenium, Any combination of these).

The solid support on which the rhenium compound is deposited can be selected from a number of porous materials. In one embodiment, the solid support is _{Al 2 O 3, Ga 2 O} 3, SiO 2, GeO 2, TiO 2, ZrO 2, SnO 2, aluminosilicate, activated charcoal, hydrotalcite anionic clay, or a mixture thereof , Preferably Al ₂ O ₃ , SiO _2, or a mixture thereof. Suitable solid supports typically have a specific surface area of from 10 to 500 m ² / g, preferably from 100 to 400 m ² / g.

Rhenium-based heterogeneous catalysts can be prepared by methods known in the art for the preparation of heterogeneous catalysts. In the general case, the preparation of a rhenium-based heterogeneous catalyst is carried out by a) impregnating a solid support with a solution of a rhenium compound, and b) subsequently drying and calcining the impregnated support.

The proportion of rhenium provided on the catalyst generally ranges from 0.01 wt% to 20 wt% of the total catalyst. The rhenium-like heterogeneous catalyst of the present invention may be subjected to further modifications to incorporate additional components which are usually suitable for adjusting the characteristics of the catalyst. For example, the catalyst may provide an activity for the hydrogenation reaction by further including a compound of a transition metal such as palladium or platinum, or may further include a compound of an alkali metal or an alkaline earth metal, ≪ / RTI >

By contacting the rhenium-based heterogeneous catalyst with the stabilizer, a stabilized rhenium-based heterogeneous catalyst can be produced. In one embodiment, the stabilizer comprises an aliphatic hydrocarbon compound, preferably an aliphatic hydrocarbon compound having 2 to 6 carbon atoms, more preferably an alkane or alkene compound having 2 to 4 carbon atoms. In the term of the present invention, a compound containing n carbon atoms will be represented by a Cn compound. That is, for example, the C2 aliphatic hydrocarbon compound may be ethane, ethene or ethyne. In a preferred embodiment, the stabilizing agent is selected from the group consisting of ethane, ethylene, propane, propylene, butane, butene or mixtures thereof.

The conditions under which the contact between the rhenium-like heterogeneous catalyst and the stabilizer are carried out needs to be carefully selected to enable stabilization of the catalyst. Preferably, the contact temperature may be in the range of 0 to 100 占 폚, preferably 10 to 60 占 폚, more preferably 20 to 40 占 폚. In a preferred embodiment, the contact conditions comprise a pressure in the range of 1 to 50 bar, preferably 10 to 30 bar. Higher temperatures and / or harsher contact conditions tend to result in catalyst deactivation by forming carbonaceous materials on the rhenium active sites.

The stabilized rhenium-like heterogeneous catalyst after being treated with the stabilizer exhibits altered hydrophobicity of the rhenium active site due to the adsorbed stabilizer. This allows the catalyst to be more selective for the olefin feedstock and less active for the catalyst poisonous material, particularly the oxygenate material.

The process according to the invention produces a stabilized rhenium-like heterogeneous catalyst which is simple, does not require harsh operating conditions and, surprisingly, has improved reaction stability and resistance to toxic substances.

Stabilized rhenium-based heterogeneous catalysts can be advantageously used in various reaction processes in which rhenium can provide suitable reaction activities (e.g., olefin epoxidation, alcohol oxidation, and, in particular, metathesis reactions).

Further, the present invention relates to a method for producing an olefin compound using the stabilized rhenium-based heterogeneous catalyst obtained by the above-described stabilization step. The method comprises contacting a stabilized rhenium-like heterogeneous catalyst with an olefin feed stream.

The object of the present invention is further achieved by a process for preparing an olefinic hydrocarbon compound comprising contacting a stabilized rhenium-like heterogeneous catalyst according to the present invention with an olefin feed stream wherein the olefin feed stream comprises a C2- C12 olefin or mixtures thereof, and the contacting is carried out at a temperature in the range of from 0 to 300 占 폚, preferably from 10 to 100 占 폚, more preferably from 20 to 60 占 폚.

Contacting the olefin feed stream with the stabilized rhenium-like heterogeneous catalyst should be performed under conditions that enable it to convert the feed stream to the desired olefin product. Preferably, said feasible conditions comprise a temperature in the range of 0 占 폚 to 100 占 폚, more preferably 10 占 폚 to 80 占 폚, and most preferably 20 占 폚 to 60 占 폚.

The olefin feed stream that can be converted to the olefin compound product in the presence of the stabilized rhenium-like heterogeneous catalyst according to the present invention can be one or more olefins having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms have. The olefin feed stream may contain olefins of a single species that can be prepared to react differently, e.g., in an auto-metathesis reaction, to produce different olefins. In more general cases, the olefin feed stream may contain one or more olefin species, wherein the olefins may react with one another to produce different olefins.

In certain embodiments of the invention, the process for preparing the olefinic compounds comprises reacting the stabilized rhenium-like heterogeneous catalyst obtained by the process according to the invention with a mixture of C2 and C4 linear olefins and / or a mixture of C2 and C5 linear olefins With an olefin feed stream comprising olefins.

In embodiments where the olefin feed stream comprises C4 linear olefins, the C4 linear olefins may be provided in the form of a mixture of C4 linear olefins, non-linear olefins, diolefins, and paraffins. Such a mixture is typically referred to as a "C4-cut" stream which is typically produced from a pyrolysis process for olefin production. Before entering the process according to the invention, it is often advantageous to treat the C4-cut with a pretreatment process. The pretreatment process may include conversion and separation of specific components, and upon contact with the stabilized rhenium-based heterogeneous catalyst according to the present invention, only the components to be actively converted to the desired olefin product can be left. Examples of C4-cut pretreatment processes can be found in U.S. Pat. No. 5,877,365, U.S. Pat. No. 5,898,091, and U.S. Pat. No. 6,075,173.

More particularly, the present invention relates to a process for the preparation of a stabilized rhenium-like heterogeneous catalyst, obtained by the process according to the invention, in the presence of an olefin feed stream and, at a possible temperature to convert said olefin feed stream to the desired olefin product, Wherein the olefin feed stream comprises an olefin selected from C2 to C12 olefins, preferably C2 to C6 linear olefins, and mixtures thereof, wherein the olefin feed stream comprises The possible temperature is preferably in the range of 0 to 300 占 폚, more preferably 10 to 100 占 폚, and most preferably 20 to 60 占 폚.

More particularly, the present invention relates to a process for the production of propylene, which comprises reacting a stabilized rhenium-based heterogeneous catalyst obtained by the process according to the invention with a mixture of C2 and C4 olefins or a mixture of C2 and C5 olefins Lt; RTI ID = 0.0 > 100 C < / RTI >

In some embodiments, the process for preparing olefinic hydrocarbons is performed at a pressure ranging from 1 to 50 bar and a WHSV (weight hourly space velocity) ranging from 0.1 to 100 h <" ¹ >

The catalysts used in the process for preparing olefinic hydrocarbons according to the present invention are generally inactivated gradually over time, so regeneration of the catalyst is required periodically. Any known technique for heterogeneous catalyst regeneration can be employed without limitation. The regeneration process generally involves desorption and combustion of adsorbed carbonaceous species while at the same time re-calcination under a flow of dilute air is carried out at a temperature in the range of from 300 to 800 占 폚, . The regeneration makes it possible, at least partially or, if appropriate, to completely restore the catalyst's catalytic performance. In some embodiments, the process for preparing the stabilized rhenium-like heterogeneous catalyst according to the present invention can conveniently be carried out immediately after the catalyst regeneration step and before the next reaction cycle.

Preferably, the process for preparing olefinic hydrocarbons according to the present invention is carried out in a fixed bed reactor.

Finally, the object of the present invention is achieved by the use of the stabilized rhenium-like heterogeneous catalyst according to the invention for catalysing the hydrocarbon conversion reaction.

The stabilized catalyst prepared by the process according to the invention makes it possible for a process (preferably a process by metathesis reaction) for the production of olefin compounds to operate with a longer operating cycle between each regeneration . For example, in the practice of the present invention, which employs a process for preparing propylene from a feed stream comprising a mixture of C4-cut and ethylene, the stabilized rhenium-based heterogeneous catalyst is a conventional, Which is about three times longer than that of the rhenium-based heterogeneous catalyst produced by the production method. In some embodiments, contacting the stabilizer with a rhenium-based heterogeneous catalyst according to the present invention comprises the steps of providing a fixed bed reactor with a rhenium-based heterogeneous catalyst, contacting the fluid stream comprising the stabilizer with the catalyst layer catalyst bed, and then contacting the stabilized catalyst with the olefin feed stream, under reaction conditions.

The following examples illustrate embodiments of the invention and are not intended to limit the scope of the invention.

<Examples>

Several catalysts were prepared according to the present invention and compared to catalysts prepared according to the prior art. The catalyst was composed as follows:

Catalyst A (comparative) is non-stabilized rhenium oxide on a gamma-alumina supported catalyst.

Catalysts B, C, D and E are rhenium oxides on the gamma-alumina supported catalyst according to the invention stabilized by flowing a stabilizing gas through the fixed bed of the catalyst at the stabilization temperature.

Catalysts F, G and H (comparative) are rhenium oxides on gamma-alumina supported catalysts pretreated by flowing stabilizing gas through the fixed bed of catalyst at high temperature.

A metathesis reaction test was conducted using catalysts A to H. The test was carried out by flowing a mixture of 12 g / h of C4 olefin and 120 sccm of ethylene through a fixed bed of 6 g of catalyst sample at a temperature of 30 DEG C and a pressure of 20 bar. Details of the test and the results are shown in Table 1.

exam
number catalyst Supply
Stream
Of
Oxygen It
content
(ppm) stabilize
gas stabilize
(Pretreatment)
Temperature
(° C) Stream  Results based on hours on 2- Butene
Conversion rate % ) Propylene
Selectivity ( % ) 2h 50h 100h 2h 50h 100h One A 0.50 none none 89.8 70.4 15.0 97.1 88.8 N / A 2 A 0.65 none none 87.4 45.2 N / A 96.4 71.6 N / A 3 B 0.65 Pro
Filen 30 85.3 51.4 32.0 98.1 81.1 71.9 4 C 0.65 Propane 30 91.0 52.6 N / A 97.2 86.2 N / A 5 D 0.65 ethane 30 89.7 55.5 41.6 97.1 86.4 81.8 6 E 0.65 Ethylene 30 88.7 69.9 56.2 98.4 88.0 81.6 7 F 0.65 Ethylene 120 80.7 53.7 ^a N / A 95.6 86.7 ^a N / A 8 G 0.65 Ethylene 150 12.8 - - 68.4 - - 9 H 0.65 Ethylene 300 7.0 - - 0 - -

Note: (1) N / A means no available data; (2) X ^a is data measured at a time of 29 hours on the stream.

From Test Nos. 1 and 2 it can be observed that the content of oxygenate material in the feed stream apparently results in inactivation of the catalyst. The results of Test Nos. 3, 4, 5 and 6 show that the use of the stabilized rhenium-like heterogeneous catalyst according to the invention significantly reduces the effect of the oxygenate material.

Further, in Test Nos. 3, 4, 5 and 6, it can be seen that various hydrocarbon compounds can be used as stabilizers of the present invention.

In Test Nos. 7, 8 and 9, it can be seen that higher temperatures do not lead to a stabilized catalyst in the light of the present invention. On the contrary, this has a considerable adverse effect on the performance of the catalyst.

Comparison results using different stabilizer stabilized catalysts and non-stabilizing catalysts (denoted "Conventional Pretreatment") in metathesis reactions of ethylene and mixed C4 streams to produce propylene are shown in FIGS.

In the metathesis reactions of ethylene and mixed C4 streams to produce propylene, the results of the comparison using a stabilizer stabilized by a stabilizer at different temperatures and a non-stabilizing catalyst ("conventional pretreatment") are shown in FIGS. 3 and 4 Respectively.

The features described in the foregoing description, the claims and / or the accompanying drawings may be, individually and in any combination thereof, material for implementing the invention in various forms.

Carrying out the invention  Best form for

The best mode for carrying out the present invention is as described in the detailed description of the present invention.

Claims (11)

A catalyst comprising a stabilized rhenium-based heterogeneous catalyst obtainable by a process comprising contacting a rhenium-based heterogeneous catalyst with a stabilizer comprising an aliphatic hydrocarbon compound at a temperature in the range of 0 ° C to 100 ° C. The stabilized rhenium heterogeneous catalyst according to claim 1, wherein the stabilizer comprises an aliphatic hydrocarbon compound containing 2 to 6 carbon atoms or a mixture thereof. The process according to any one of the preceding claims wherein the stabilizer comprises an alkane and / or an alkene compound having from 2 to 4 carbon atoms, preferably a stabilizer, such as ethane, ethylene, propane, propylene, Rhenium heterogeneous catalyst. 4. The stabilized rhenium heterogeneous catalyst according to any one of claims 1 to 3, wherein the contacting is carried out at a temperature in the range of from 10 to 60 DEG C, preferably in the range of from 20 to 40 DEG C. The method of any one of claims 1 to 4, wherein the rhenium-based heterogeneous catalyst comprises a rhenium compound on a solid support, wherein the solid support is selected from the group consisting of Al ₂ O ₃ , Ga ₂ O ₃ , SiO ₂ , GeO ₂ , TiO ₂ , ZrO ₂ , SnO ₂ , aluminosilicate, activated carbon, hydrotalcite, anionic clay or mixtures thereof, more preferably the solid support is selected from the group consisting of Al ₂ O ₃ , SiO ₂ Or a mixture thereof. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; 6. The method of claim 5, wherein the rhenium compound is a rhenium element and / or a rhenium compound, wherein the rhenium compound is selected from the group consisting of rhenium oxide, rhenium hydride, rhenium sulfide, rhenium carbide, Heterogeneous catalyst. A process for preparing an olefinic hydrocarbon compound comprising contacting a stabilized rhenium-like heterogeneous catalyst according to any one of claims 1 to 6 with an olefin feed stream, wherein the olefin feed stream comprises a C2 to C12 olefin or And mixtures thereof, wherein said contacting is carried out at a temperature in the range of from 0 to &lt; RTI ID = 0.0 &gt; 300 C. &lt; / RTI &gt; 8. The process of claim 7, wherein the olefin feed stream comprises olefins selected from C2 to C6 linear olefins or mixtures thereof, preferably the mixture comprises a mixture of C2 and C4 linear olefins and / or C2 and C5 linear olefins By weight based on the total weight of the olefinic hydrocarbon compound. 9. Process according to claim 7 or 8, wherein the contacting is carried out at a temperature in the range from 10 to 100 DEG C, preferably in the range from 20 to 60 DEG C. 10. A process according to any one of claims 7 to 9, wherein the olefinic hydrocarbon compound is produced in a fixed-bed reactor. Use of a stabilized rhenium-based heterogeneous catalyst according to any one of claims 1 to 6 for catalysing a hydrocarbon conversion reaction.

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